And they are typically encased in a casing with a heat sink and built in fans.

Since they don’t require a ballast, you can plug them directly into the wall.

The diodes on an LED light run on average ⅓ to 1 watt of power.

Meaning your lights offer a bunch of power at a third of the energy used.

But some lights have 1W, 3W and even 5W diodes now.

LED Grow Lights vs. HPS

If you’ve been growing marijuana for a long time, then you probably know all about HPS grow lights.

After all, they were the hot new kid on the block at one point in time.

Most growers that have been resistant to the change think their yields are good enough and that more expensive LED setup costs don’t outweigh the lower monthly electric bills.

If that sounds like you, I’m glad to hear you’re at least now thinking about giving LEDs a shot.

The reasons we think LED win out over HPS every time are simple:

Heat

​Dealing with temperatures that are too high is a big enough problem on its own (especially if you live closer to the equator).

Your lights shouldn’t add to the fire.

The temperature difference between LED lights and HPS lights is almost a biggest enough selling point on its own.

The temperature difference between LED and HPS lights is almost a biggest enough selling point on its own.

Plus, having cooler lights saves you money by not having to buy extra exhaust fans.

Now, if you live in a cooler climate, you might think about staying with HPS lights.

The HPS lights would help keep your grow room warm enough to grow cannabis, but this is rare.

Light Intensity

​When it comes to light intensity HPS and LED are pretty damn close.

But, HPS definitely has the upper hand. ​

Keep in mind , though, it's not lumens (light intensity) that plants need but rather the right wavelengths.​

Yield

​What’s our goal when growing our own cannabis?

Fat amounts of bud!

So, how do HPS and LED lights compare when it comes to yield?

On average, you’ll get around .5 grams per watt with an HPS light. Full spectrum LED grow lights, however, give you anywhere from 1 gram to 1.5 grams per watt.

If you can 3x your yield just by investing in new lights, it seems like a pretty easy answer to me!

Lifespan

​This is another area where LED grow lights just absolutely crush it.

With an HPS light you can expect about 10,000 hours (sounds like a lot, right?).

Well, with an LED 50,000 is the low end with some lasting all the way up to 100,000 hours!

Distance from Plants

Because of the massive amounts of heat exuded by HPS lights, you don’t have as much freedom as to where you can place your lights.

With LED lights, however, you can get them closer to your plants making it easier for them to absorb the light.

The Spectrum of Light

​LED lights let you custom tailor the wavelength you’re giving your plants, and most come preset for the perfect type of light your plants need during the vegetative and flowering cycles.

HPS lights, on the other hand, emit the entire wavelength, so a lot of the light goes unused by your plants.

More Benefits of Using LED Grow Lights

We’ve already touched on quite a few benefits of using LED lights, and we’ll dive deep into a lot more later on.

Most of us don’t have even a full room to devote to growing our marijuana.

No, most of us are either closet growers or we're lucky enough to have an awesome grow tent or a grow cabinet.

Whatever you may be growing in, LED's will be your best choice because they are:

Smaller and easier to install: LED lights are plug and grow and use chips to convert energy into light. So, you don’t need extra equipment just to run your lights.

Easier to plan ventilation with: You don’t have to worry about running extra ventilation just to remove the heat caused by your lights.

Give you control over the spectrum: You control the wavelengths you provide your plants allowing you to give them exactly what they need during both stages of growth instead of the one size fits all mentality of HPS, MH or fluorescent lights.

And that’s not even considering the energy savings!

How to Choose an LED Grow Light

When it comes to outfitting your garden, there are so many options with every single thing you need to buy, and it’s no different for grow lights.

But there are a few specific things you should look for when making your decision.

After all, the lights can end up being the most expensive part of your garden, and you don't want to make an investment that you end up regretting!

Light proportion

The spectrum of your light needs to be at the front and center of your decision.

Grow lights for cannabis need to include red and blue wavelengths and also ultraviolet and infrared.

It’s also crucial the light be good for all stages of growth!

Believe me.

Some aren’t, so you need to pay attention to the spectrum they say the light offers.

For instance, if your light just runs heavy on red, it will waste a lot of energy of wavelengths that won't be absorbed by the plant during the vegetative stage.​

Energy saving and great power efficient

When it comes to LED lights, you want them to produce more light while using less electricity.

Pay attention to the ratio of equivalent wattage and actual power drawn wattage.

Lights Lifespan

As mentioned earlier, one of the biggest advantages of a LED is the lifespan, right?

If you have the option of one that will last 50,000 hours vs. 100,000 hours you need to consider if the extra cost up front is worth having a longer lasting light.

Low Levels of Heat Output

Not only is low heat output good for your cannabis but it also adds to the lights durability.

You want the light to offer some built in fans to help cool the lights down even more.

Good LED lights have aluminum heat sinks built into the system to keep them cool.

Constant Current Driver Circuit

LED circuit drivers should constantly be supplying a direct current of energy and should regulate the intensity in response to any changes in temperature.

Should You Choose a Full-spectrum LED?

To understand what a full-spectrum LED grow light is you need to know a little about the spectrum they are referring to.

So, to be honest, the term “full-spectrum” does not mean the light produces every wavelength imaginable, but rather that it’s producing the wavelengths of the PAR spectrum.

You must also keep in mind that grow light companies do not have to get their lights tested and approved to be called full-spectrum, so you can only trust the term as far as you can trust the company behind the light.

So, do you need a full-spectrum light?

Your plants will benefit greatly from a light that produces all of the wavelengths of the PAR spectrum at a strong and continuous rate, so yes!

That’s not to say plants don’t use wavelengths outside of the PAR spectrum.

But they are either too intense or too weak to be of any use during photosynthesis.

Also, photons in the PAR range contain the perfect amount of energy for the plant's electrons without causing damage.

How do Plants Absorb Light?

Stay with me here.

We are almost through the very science-intensive portion of this guide!

To absorb light, plants use pigments.

The most abundant pigment they have is chlorophyll which they use to capture both blue and red light.

Other pigments that absorb light are carotenes and xanthophylls that work to harvest various wavelengths before passing it over to photosynthesis.

You should also know that plants absorb green light deeper into their tissue that any other color.

That’s why green light can make photosynthesis run more efficiently in a plant.

The most abundant pigment they have is chlorophyll which they use to capture both blue and red light.

This happens because the chloroplasts that contain chlorophyll end up becoming saturated.

When the choloplasts become saturated, they allow green to pass deeper into the plant tissue.

Once there, it’s bounced around until it’s absorbed by an unsaturated chloroplast or another pigment.

How Many Watts Do You Need for the Best Yield?

Now I know that might have seemed a little heavy on the science, but it’s important for you to understand every aspect of your grow room fully.

And since the lights are just about the single most important factor, you should spend time studying them.

But now on to the stuff that moves the needle:

How many watts you need per square foot with an LED.

When it comes to LED lights, it’s not the watts are important.

Using watts to determine how much lighting is sufficient for a given area is a legacy system built upon HPS lights.

Still, it’s the most used terminology even with the rise of LEDs, so we’ll use it.

First, you need to know that when a LED light is advertised as 300 watts, it’s referring to its HPS and metal halide wattage equivalent and that it's only drawing in around 135 watts of power.

The number you need to know if a light will work for your grow tent is the true power and not the equivalent.

On average, with LED lights, you need 32 watts per square feet of actual draw power to grow cannabis.

This is the wattage needed during flowering, while in the vegetative stage you might consider running around 50% of this.

You can use this calculator to see how many watts you need quickly:

Tips to Avoid Problems with LEDs

There is some subtle differences between growing with old school lights and LED lights.

The low heat output might trick you into thinking you can put the light practically sitting on the plant and call it a day, but be warned.

While there isn’t an exact science to it, LED grow lights need to be placed around 12-18” from the top of your plants.

If you let the lights stay too close to the plants, not only will it stunt their growth, but LED lights can cause your cannabis leaves to turn discolored and closely resemble a nutrient deficiency.

Obviously, this can be a problem if you start messing with the nutrients when the problem is nowhere near the cannabis soil.

If you spot discoloration, pay attention to see if it’s near the lights or not.

If it is, you probably found your culprit and then move your lights back to prevent further light burn.

LED lights that are too close can also bleach the top of your buds.

This is especially common during flowering after the plants have been under the LED for months.

You also need to keep an eye out for colas that are standing way above your other plants.

Nothing on this website should be considered legal or medical advice or as a substitute for legal or medical advice. Please respect the marijuana laws in your state.

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